1. Field of the Invention
The present invention relates to a method for enhancing a resource utility rate for a wireless communications system and related communications device, and more particularly to a method of managing a high-speed downlink operation to enhance a resource utility rate for a wireless communications system and related communications device.
2. Description of the Prior Art
The third generation (3G) mobile telecommunications system has adopted a Wideband Code Division Multiple Access (WCDMA) wireless air interface access method for a cellular network. WCDMA provides high frequency spectrum utilization, universal coverage, and high quality, high-speed multimedia data transmission. The WCDMA method also meets all kinds of QoS requirements simultaneously, providing diverse, flexible, two-way transmission services and better communication quality to reduce transmission interruption rates. Through the 3G mobile telecommunications system, a user can utilize a wireless communications device, such as a mobile phone, to realize real-time video communications, conference calls, real-time games, online music broadcasts, and email sending/receiving. However, these functions rely on fast, instantaneous transmission. Thus, targeting at the third generation mobile telecommunication technology, the 3rd Generation Partnership Project (3GPP) provides High Speed Package Access (HSPA) technology, which includes High Speed Downlink Package Access (HSDPA) and High Speed Uplink Package Access (HSUPA), to increase bandwidth utility rate and package data processing efficiency to improve uplink/downlink transmission rate.
For an HSDPA UE, physical channels include a high speed physical downlink shared channel (HS-PDSCH), for transferring payload data, and a high speed physical control channel (HS-DPCCH) for uploading an acknowledgement/negative acknowledgement (ACK/NACK) and a channel quality identifier (CQI). As for the media access control (MAC) layer of the HSDPA UE, a MAC-hs entity utilizes a transport channel of High Speed Downlink Shared Channel (HS-DSCH) for receiving data from the physical layer. In addition, a shared control channel for HS-DSCH (HS-SCCH) is used as a physical downlink channel, responsible for transmission of control signals, such as demodulation information, corresponding to HS-DSCH.
Besides the CELL_DCH state, a similar high speed downlink reception operation is also provided in CELL_FACH, allowing the UE in CELL_FACH to monitor HS-DSCH for data reception to improve a peak data rate, a signaling delay, a state transition delay, download times and flexible cell capacity. This high speed downlink reception operation is hereinafter called HS-DSCH reception in the CELL_FACH state. A UMTS radio access network (UTRAN) enables the HS-DSCH reception in the CELL_FACH state by including the parameters, related to radio resource control (RRC) configuration of HS-SCCH, HS-DSCH and a common H-RNTI, in the system information broadcast. In addition, the UTRAN may reconfigure an H-RNTI variable in the UE by dedicated RRC signaling.
For the HS-DSCH reception in the CELL_FACH state, the basic downlink channel configuration consists of one or several HS-PDSCHs along with a number of separate HS-SCCHs. Since there is no dedicated channel in the CELL_FACH state, no HS-DPCCH will be used for uplink signaling. HS-DSCH-related uplink ACK/NACK signaling is not supported. The MAC-hs can perform retransmission without uplink signaling. The measurement result on a random access channel (RACH) used for uplink transmission at the UE side can be used for link adaptation.
For enabling the HS-DSCH reception in CELL_FACH state, the RRC specification specifies that the UE shall start to receive HS-SCCH(s) and HS-DSCH with the common H-RNTI after sending an RRC CONNECTION REQUEST message to the UTRAN during an RRC connection establishment procedure. The common H-RNTI is selected from a list of candidate common H-RNTIs according to a formula “A” as follows:
A: Index of selected Common H-RNTI=Initial UE Identity mod K,
where K is equal to the number of candidate Common H-RNTIs, and “Initial UE Identity” represents an identity of an UE included in the RRC CONNECTION REQUEST message. For example, if K is equal to 4, Index of selected Common H-RNTI could be 0, 1, 2 or 3. In this way, the UTRAN can group the UEs in the same cell with different values of the common H-RNTIs for transport channel allocation. Thus, all UEs in the same cell do not use the same radio resources to receive packets.
The UTRAN responds to the RRC CONNECTION REQUEST message with an RRC CONECTION SETUP message indicating the UE CELL_DCH or CELL_FACH state to be entered. In the RRC specification, the UE reselects an index of selected Common H-RNTI when entering the CELL_FACH state according to a formula “B” as follows:
B: Index of selected Common H-RNTI=U-RNTI mod K,
where U-RNTI is included in the RRC CONECTION SETUP message and is received by the UE after the UE enters the CELL_FACH state.
Obviously, the formulas “A” and “B” use different parameters to generate the index of selected Common H-RNTI. The UE obtains the common H-RNTI based on the formula “A” when sending the RRC CONECTION REQUEST message. This reveals that the UE uses the formula “A” in idle mode. On the other hand, the UE reselects the common H-RNTI based on the formula “B” after receiving the RRC CONECTION SETUP message. This reveals that the UE uses the formula “B” in the CELL_FACH state.
In addition, the UE determines whether to perform the HS-DSCH reception in the CELL_FACH state or not by determining an HS_DSCH_RECEPTION_CELL_FACH_STATE variable. For performing determination of the variable, the UE must have selected the common H-RNTI based on the formula “B” and already been in the CELL_FACH state. In other words, the HS_DSCH_RECEPTION_CELL_FACH_STATE variable is only applied to the situation where the common H-RNTI is selected based on the formula “B”.
When the RRC connection procedure is accomplished, the UTRAN may configure the UE to enter the CELL_DCH state without allocating HS_DSCH. Besides, the UE has selected a common H-RNTI to use based on the formula “A” before entering the CELL_DCH state. As can be seen from the above, this means that the UE has no chance to determine the HS_DSCH_RECEPTION_CELL_FACH_STATE variable for stopping the HS-DSCH reception in the CELL_FACH state. As a result, the UE keeps monitoring HS-DSCH and HS-SCCH according to the common H-RNTI after entering the CELL_DCH state. However, the UTRAN does not configure HS-DSCH with the parameters used before the UE enters the CELL_DCH state. Therefore, continued monitoring of HS-DSCH by the UE only results in a waste of the UE power.
Even though the UE is indicated to enter the CELL_DCH with HS_DSCH, the UE needs to stop using the parameters received from the SIBs type 5/5bis or 6, and then uses new parameters via dedicated RRC signaling to monitor HS-DSCH and HS-SCCH.